The overall aim of this proposal is to develop a new method for the objective analysis of pediatric PET image data. The application of voxel-based image analysis methods is a major contribution in evaluating adult PET image data. However, these methods require the warping of the data to a standard anatomical map for comparison of patient groups to large control groups. Due to the changes in brain size and tracer distribution with age as well as the difficulty in obtaining control data in children, a different approach needs to be developed for the analysis of pediatric data We propose the development of a software tool able to perform geometric parcellation of the cortex based on high resolution MRI image volumes yielding standardized cortical volumes which scale proportionally to the size and shape of each individual brain As a result, the geometric parcellation allows the definition of cortical volumes created at varying resolution levels. At each resolution level, intensity histograms (representing PET tracer concentration) obtained from the standardized cortical volumes can be analyzed and compared across groups In particular, this method allows the detection of abnormal increases or decreases of tracer activity in an individual cortical volume based on statistical comparison with a group of normal adult histograms, all obtained from the same geometric location. Three specific aims are to be addressed in this proposal (1) To develop a software tool which allows geometric parcellation of the cortex and to assess the effect of varying resolution levels on the distribution of the intensity histograms, (2) To determine the accuracy of the software tool for localization of functional PET abnormalities using phantom measurements, and (3) To apply the developed software package in order to define objectively the extent and location of uni- or bilateral cortical abnormalities in children with epilepsy Specifically, this approach will allow the definition of abnormalities without the need of preselecting the side of the abnormality nor of predetermining whether the abnormality consists of tracer decrease or increase. In addition, the proposed software tool will facilitate the study of developmental patterns in children allowing an improved objective localization of uni- or bilateral PET abnormalities in children with developmental disorders. If successful, this determination will impact upon a large number of children with uncontrolled epilepsy as well as other neurological disorders.